Chlorination of butadiene



United States Patent Office 3,406,215 Patented Oct. 15, 1968 3,406,215CHLORINATION F BUTADIENE Howard Emil Holmquist, Wilmington, Del.,assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., acorporation of Delaware No Drawing. Filed Oct. 23, 1965, Ser. No.504,167 4 Claims. (Cl. 260655) ABSTRACT OF THE DISCLOSURE Process forthe chlorination of butadiene by reacting butadiene with an organicsolvent solution of cupric chloride in the presence of a second chloridesalt, said cupric chloride and said second chloride salt being solublein said solvent and recovering 1-chloro-1,3-butadienc and2-chloro-l,3-butadiene.

Chlorobutadienes are valuble compounds from which useful polymericmaterials may be synthesized. However, these compounds are manufacturedby expensive procedures. In one method, they are produced from acetyleneby a process which comprises dimerizing the actylene to vinylacetyleneand hydrochlorinating the vinylacetylene to the chlorobutadienes. Inanother method, 1,3-butadiene is first chlorinated by addition and thendehydrochlorinated to the chlorobutadienes.

The reaction of 1,3-butadiene with cupric chloride supported on pumicein the temperature range of 200-330 C. has been described by R. P.Arganbright and W. F. Yates in Journal of Organic Chemistry, vol. 27,pages 12054208 (1962). In this reaction the products consisted of 98mole percent of various dichlorobutenes and only 2 moles ofl-chlorobutadiene.

In its broadest description this invention is a process for thechlorination of butadiene which comprises contacting and reactingbutadiene, under substantially anhydrous conditions, at a temperaturebetween about 100 C. and about 250 C. with an organic solvent solutionof cupric chloride, in the presence of a second chloride salt selectedfrom alkali metal chlorides, calcium chloride, ammonium chloride andtetraalkylammonium chloride, the organic solvent being one in which thesecond chloride salt is at least slightly soluble, and thereafterrecovering from the reaction product 1 chloro 1,3- butadiene and2-chloro-1,3-butadiene.

While any tetraalkylammonium chloride may be used, there is noparticular advantage to be gained in using compounds in which each alkylgroup contains more than twelve carbon atoms. Examples of suitabletetraalkylammonium chlorides include tetramethylammonium chloride,tetraethylammonium chloride, tetrabutylammonium chloride,dodecyltrimethylammonium chloride, and the various other compounds inwhich the alkyl groups are branched or unbranched and in which the alkylgroups are all the same or are different. Of the alkali metal chlorides,lithium chloride is preferred because of its good solubility in polarorganic solvents.

The requirements for the organic solvent to be used in carrying out theprocess of this invention are:

(a) It should be liquid under the conditions of the reaction.

(b) It should be resistant to reaction with the reagents.

(c) It should dissolve significant amounts of the salts being used inthe reaction. In particular it should be able to dissolve, under theconditions of the reaction, at least 0.1 gram mole each of cupricchloride and of the second chloride salt per liter of solvent. If nosignificant amount of the second chloride salt dissolves in the solvent,the product will contain no significant amount of chloroprene. Thereshould be used at least 0.2 gram mole of the second chloride salt pergram mole of cupric chloride. In general, because of solubilitylimitations, there is little practical advantage in using more than 35moles of the second chloride salt per mole of cupric chloride, eventhough the ratio of 2-chlorobutadiene to l-chlorobutadiene in theproducts increases with increasing ratios of the second chloride salt tocupric chloride.

In order for the salts to be sufiiciently soluble, the solvent should bepolar in character. Examples of suit able solvents include loweraliphatic carboxamides and their N-alkyl and N,N-dialkyl derivatives,lactams, containing 5 to 7 atoms in the ring and their N-alkylderivatives, lower dialkyl sulfoxides and sulfones, cyclic alkylenesulfones containing 5 to 6 atoms in the ring, and N-alkylatedphosphoramides.

The lower alphatic carboxamides may be represented by the formula:

N-C-Z Y/ 0 in which X, Y and Z may be hydrogen, or lower alkyl radicalscontaining up to four carbon atoms. Specific examples include formamide,acetamide, propionamide, butyramide, isobutyramide, valeramide,N-ethylformamide, N-butylacetamide, N-butylbutyramide,N-propylbutyramide, N,N-dimethylbutyramide, N,N-diethylpropionamide, N,Ndipropylacetamide, N,N dipropylpropionamide, N,N dibutylformamide, N, Ndibutylbutyramide, N ethyl-N-methylactamide, and N,Ndimethylisovaleramide.

The lactams may also be represented by the formula given above when Xand Z together form an alkylene radical containing three to five carbonatoms.

The lactams which may be used include 2-pyrrolidone, 2-piperidone, andcaprolactam and their N-alkyl derivatives in which the alkyl radicalsare lower alkyl containing one to four carbon atoms. Examples of theN-alkyl lactams are 1-methyl-2-pyrrolidone, l-isopropyl-Z-pyrrolidone, lethyl 2 piperidone, l butyl 2 pyrrolidone, and N-methylcaprolactam.

Examples of the lower dialkyl sulfones and sulfoxides which may be usedare those in which each alkyl group contains one to four carbon atomssuch as dimethyl sulfone, dimethyl sulfoxide, diethyl sulfone, diethylsulfoxide, dibutyl sulfone, dipropyl sulfoxide and methyl butylsulfoxide. Examples of cyclic alkylene sulfones include tetramethylenesulfone and pentamethylene sulfone.

Another class of solvents which may be used includes the hexaalkylphosphoric triamides in which the alkyl groups contain one to fourcarbon atoms. Examples include hexarnethyl phosphoric triamide,hexaethyl phosphoric triamide, hexabutyl phosphoric triamide, andhexapropyl phosphoric triamide. Hexalkyl phosphoric triam ides havingmixed alkyl groups can also be used.

Of the solvents discussed above, the preferred ones are the N,N-dialkylcarboxamides and the N-alkyl lactams. The most preferred solvent isN,N-dimethylformamide because of its good solvent power and readyavailability.

The amount of solvent is not critical except that a sufficient amountshould be used to provide a liquid medium for the reaction under theconditions being used.

The reaction should be carried out under essentially an hydrousconditions to keep side reactions at a minimum. By essentially anhydrousis meant that precautions are taken to exclude water from the reactantsand the reaction system.

The reaction may be carried out at temperatures ranging from about C. toabout 250 C. Below about 100, C. the conversion of starting material istoo low to be of practical use. In general, there is no reason to usetemperatures above about 250 C. since most useful solvents boil belowthis temperature. The preferred temperawhich is fitted with a condenserwhich is also cooled by solid carbon dioxide and acetone. When theintroduction of butadiene is stopped, nitrogen is passed through thereaction mixture for 10 minutes to sweep out any mateturewill dependsomewhat on the solvent being used. In 5 rials more volatile than thesolvent. To the contents of the case of dimethylformamide, the preferredtemperathe receiver is added 5 ml. of ethyl ether. The receiver is turerange is 145-153 C. allowed to warm almost to room temperature whilemost It is generally most convenient to carry out the reacof thebutadiene is distilled into a Dewar trap cooled with tion at atmosphericpressure, although higher or lower a mixture of acetone and solidcarbondioxide. To recover pressures may be used. A temperature above theboiling any products entrained with the butadiene, 5 ml. of ethyl, pointof the particular solventbeing employed will necesether is added to thecontents of the Dewar trap, and the sitate the use of superatmosphericpressure. contents are allowed to partially evaporate. The residues Thetwo isomeric chlorobutadienesmay be separated ffOm the tWOBVflPOIQtiOIIS are analyzed y gas Chromafrom each other by gaschromatography or by fractional tog-raphy on a commerclal' gaschromatographic instrudistillation i an ffi ie t ol 1 ment using a250-cm. glass column packed with calcined The process may be operated ineither a batch or a condratomite aggregates having adsorbed thereon bytinuous manner. It is particularly adaptable to a continu- Weight ofpolyethylene glycol having a molecular weight ous process in which theproduct stream is removed from of 15,00020,0003E1I1d a SOflefiiIlg Willt0f The the reaction vessel, and the unused butadiene is removed amountsf 1- 0 tadiene and h oropr ue shown from the products and recycled tothe reaction vessel. The 20 y he ana ys s are used to calculate thepercent converby-product, cuprous chloride, formed during the processsion based on the amount of cupric chloride introduced may be reoxidizedto cupric chloride, for example, by treatto the reaction vessel usingthe following formula? ment with chlorine moles of roduct Thechlorobutad1enes prepared by the process are start- P61136115- r8 0n=100 v 1/2 moles of 01101 mg materials for the preparation of polymers.Part1cular- 2 y the chloroprene, on p y at yields highly The data fromthe various examples are shown in the fill synthetic elastomers. Inaddition, the 1-chloro-1,3- bl The f ll i abbreviations are usedbutadiene may be used as a startmg materlal for other TMAC h 1 rcompounds. For example, it may be converted to a Grig- E g y .ammomumchlpnde nard reagent as described in US. Patent 3,083,242 and DMF '3 g pChloride thus used for the preparation of a wide variety of organicylformamlfie compounds. DMAC-N,N-drmethylacetamide EXAMPLES2-Pyr2-Pyrrolidone DMSO-dimethyl sulfoxide The examples are carned outusmg the following gen- 35 HMP h h 1 h h id eml P C F TMS-tetramethylenesulfone (tetrahydrothiophene The reaction 1s carried out in elther a 250ml. three- 1,1-dioxide) TABLE Second Mole Butadiene Solvent Mole ProductExample Vessel CuCl2(A), Nature chloride Ratio, Temp, Addition, Ratio,conversioni wt., g. salt (B), BIA 0. hr. Nature ml. 01/13 5 wt., g.Percent-a Percentfl 0.7 M01 18.9 0.2 150 5 Mr 2 0.0 LiCl 70.0 32.2 150 5iii/1F 50% i1? i313 12.4 L101 4.0 1.0 150 0 DMF 125 12 4.7 0.4 31.7 KCl1 5.5 0.3 150 5 DMF 500 100 3.2 0.032 23.2 NaCl 1 4.3 0.5 150 5 DMF 40045.5 3.3 0.073 11.0 0201-; 12.2 1.2 100 5 DMF 125 5.0 10.4 2.1

0.5 TMAC 11.8 2.2 150 5.5 DMF 125 125 1.55 0.75 13.7 D TMAC 30.2 1.3 1535 DMF. 125 3.3 5.1 1.0 11.5 L 01 13.0 5.2 100 5 DMAC 125 2.0 3.5 1.213.9 L 01 19.0 4.5 150 3.5 2-Pyr 125 37 4.0 0.13 10.2 L101 15.7 4.0 1505.5 DMso 125 4.0 2.7 0.0 20.1 L1G] 23.0 5.3 150 5 HMP 500 500 0.17 0.4251.4 L101 01.3 3.8 250 3. 25 TMS 500 2.1 8.0 as 9.3 L101 1.5.5 5.0 150 5DMF 100 2.2 2.2 1.0

HMP 25 15.2 None None 150 5 DMF 125 1,000 11.7 0.01

1 Added at the rate of 50-70 mlJmin.

2 011 50.1 g. added, 44.6 g. were recovered by filtration at 100 C.after react on.

3 01 10.0 g. added, 5.2 g. were recovered by filtration at 100 C. afterthe reaction.

necked round-bottomed flask (RBF) or a l l. resin kettle (RK), as shownin the table. The vessel is flushed out with introgen and the solvent isplaced in the reaction vessel. The anhydrous salts are weighed bydifierence and added rapidly in a stream of nitrogen to avoid contactwith atmospheric moisture. The contents of the vessel are heated to thedesired temperature while nitrogen is bubbled through, with stirring todissolve the salts. While the contents of the vessel are maintained atthe desired temperature, gaseous butadiene is introduced with rapidstirring at a rate of about 40 ml./min. (at about 27 C. and atmosphericpressure) unless indicated otherwise, for the period of time shown inthe table. Volatilized products are trapped in a receiver which iscooled with a mixture of solid carbon dioxide and acetone (about -78 C.)and 4 Based on (311012. 5 0: 1s 1-chloro-1,3-butadiene, 6 is2-chloro-1,3-butadiene.

What is claimed is:

1. Process for the chlorination of butadiene which comprises contactingand reacting butadiene, under substantially anhydrous conditions, and ata temperature between about C. and 250 C., with an organic solventsolution of cupric chloride, in the presence of from at least 0.2 to 35gram moles, per gram mole of cupric chloride, of a second chloride saltselected from alkali metal chlorides, calcium chloride, ammoniumchloride, and tetraalkylammonium chlorides, said organic solvent (1)providing a liquid medium for the reaction, (2) being polar and (3) onein which at least 0.1 gram mole of said cupric chloride and at least 0.1gram mole of said second chloride salt, per liter of said solvent, aresoluble therein, and recovering from the reaction productl-chloro-l,3-buta- 5 diene and 2-chloro-1,3-butadiene, said organicsolvent (V) hexaalkyl phosphoric triamides, the alkyl groups beingselected from thereof having from 1 to 4 carbon atoms.

(I) an organic compound having the formula: 2. The process of claim 1 inwhich the said solvent is dimethyl formamide. X 5 3. The process ofclaim 2 in which the temperature of reaction is from 145 to 153 C. 4.The process of claim 1 in which the second chloride Y 0 salt is lithiumchloride.

References Cited in which X, Y and Z are hydrogen or alkyl radicals 10having from 1 to 4 carbon atoms or in which X and UNITED STATES PATENTSZ taken together are an alkylene radical having from 3,061,653 10/ 1962Stewart 260-655 3 to 5 carbon atoms. 3,184,514 5/ 1965 Sennewald et al260-654 (II) dialkyl sulfoxides, the alkyl groups thereof having 15FOREIGN PATENTS from 1 to 4 carbon atoms. (III) dialkyl sulfones, thealkyl groups having from 1 918,062 2/1963 Great Bfltalnto 4 carbonatoms. (IV) cyclic alkylene sulfones having 5 to 6 atoms in BERNARDHELFIN Prlmary Exammef' the ring. I. BOSKA, Assistant Examiner.

